>If this sentence is supposed to mean that the pig and the boar share
>38 chromosomes out of a larger total, the words between the comma and
>'with' should not be there.
But this sentence is not supposed to mean that, because these words are there.
LOL.
Look, you keep grasping at straws.
The words "those of domestic pig and wild boar specimens with 38 chromosomes" are the head (nominative) of the absolute construction. If you want to grasp something, grasp the whole thing.